How Battery Storage Works

How Battery Systems Work


During the day the battery system is charged by electricity generated by the Solar PV Panels


Smart batteries use software to coordinate electricity production, usage history, electricity tariffs and weather patterns to optimise when the stored energy is used.


Energy is discharged from the battery during times of high usage.

Battery storage systems are rechargeable systems that store energy from the Solar PV system and provide energy to a home or a business. The systems work by converting the DC energy produced by the Solar Panels and storing it as DC power, before converting to AC for later use. The higher the battery’s capacity the larger the solar system is can charge.

When a battery storage system is installed the system will store excess electricity that is generated onsite instead of sending it back to the National Grid. Electricity will only go back to the grid when your battery is fully charged and electricity will only be drawn from the grid when the battery is depleted.

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What Are The Options?

Battery technologies are developing fast and therefore to get the right solution for your home or business you are welcome to ask one of our energy consultants to visit. There are a few key points that are valuable to understand:

Capacity is the amount of energy in kWh that a battery can store. Batteries should never be drained completely. However, some are misleading and sold under the heading ‘total capacity’. Useable capacity is the specification that you need to know. For example a Tesla Powerwall advertised at 14kWh actually has 13.5kWh useable capacity.

A cycle is one complete discharge and one complete charge. In reality, the battery will not work in this way. A battery might only discharge 40% and then recharge 40% given the average demands on the system. This would be 2/5th of a cycle. Often battery manufacturers will warrant the battery for the number of cycles and therefore it is important to work out how many kWh your battery will delivery over it’s warrantied lifetime based on your average cycle.

An average kettle will need 2000 watts to boil water for a cup of tea. If your battery system only delivers 800w then it won’t be very effective. Likewise, if you are generating 5kW from  your Solar PV array, but the battery can only take on 3kW then 2kW will be heading to the grid, wasting precious free energy for the site. Therefore, it is essential to check the power output of the battery system and the onsite requirements.

Perhaps the most important question is to ask what your likely future requirements might be. For example, are you planning to have EV charging? A larger capacity system can keep the house or business premises running and charge EV vehicles overnight. Grid trading is also an exciting option. Larger battery systems will mean more charging at lower rates and more to sell back to the grid at peak rates.

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